OPTIMIZATION OF THE GATE DRIVER PARAMETERS IN A WIDE BAND GAP MATERIAL BASED DC-DC CONVERTERS FOR HIGH POWER APPLICATIONS

DC-DC converters are being used for power management and battery charging in electric vehicles (EVs). To further the role of EVs in market, more efficient power electronic converters are needed. In this scenario, wide band gap (WBG) devices, such as silicon carbide (SiC) and gallium nitride (GaN), are inevitably the future of power electronic converters, because they provide higher frequency and lower power loss. However, their high di/dt and dv/dt transients result in higher electromagnetic interference (EMI). On the other hand, some gate driver parameters such as gate resistor (RG) have contradictory effect on efficiency (\eta) and EMI. So the fast transition switching time makes the gate driver design a challenging task. The idea of the thesis is to investigate the values of these parameters using a multi-objective optimization method to optimize \eta and EMI at the same time. To this aim, first, the effect of high/low side RG on \eta and EMI in the half-bridge configuration is studied. Then, the objective functions of the optimization problem are obtained using a numerical regression method on the basis of the experimental tests. Then, the values of the gate resistors are obtained by solving the multi-objective optimization problem. Finally, \eta and EMI of the converter in the optimum gate resistor design are compared to those in the conventional design to validate the effectiveness of the proposed design approach. In particular two distinct cases are discussed and presented. The first case, a SiC-based half-bridge converter prototype was tested and the objective functions considered are efficiency and conducted EMI current which passes through the power ground (PG), considering the maximum amplitude of this ground current in \muAdB ({\hat{I}}_{GR}) as the EMI level of the converter. In the second case, a GaN-based half-bridge converter prototype was tested and the objective functions considered are efficiency and the near-field EMI of the GaN devices to evaluate the EMI level of the converter.